Black smoke emitted by diesel vehicles is a major environmental problem in urban areas because this pollutant:

1. contains tiny inhalable soot particles coated in highly toxic oilCorrect answer!
2. contains oil droplets that settle on the skin and cause fungal infections
3. causes respiratory disease because of its high carbon-dioxide content
4. causes heart attacks because of its high carbon-monoxide content

Explanation

The correct answer is option 1 (contains tiny inhalable soot particles coated in highly toxic oil). This question assesses Citizenship and environment; this alternative directly meets the conditions in the prompt and the road-safety rules. The other alternatives broaden, narrow, or depart from the stated conditions and therefore should not be selected. Under the current rule, the difficulty is 3 on a scale from 1 to 5.

Source

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